The goal of this project is to examine the reward response of brain circuitry underlying some of the inter individual variability in the risk for substance use disorders (SUDs). For this purpose, a college-age sample that is at the peak risk for the development of SUDs will be studied using functional neuroimaging. Subjects will be selected on the basis of high and low scores in a validated measure of impulsivity-sensation seeking, a well-recognized risk factor for the development of SUDs. Participants will be studied during the performance of a monetary reward task (the Monetary Incentive Delay task) that is felt to be particularly relevant for this population sample and the goals of this proposal. Functional MRI (fMRI) will be employed to detect activation throughout the brain in response to this task, in combination with psychological testing to assess the underlying affective state and personality traits of the volunteers. The proposed experiments will explore whether brain circuitry involved in reward processing also underlie individual differences in behavioral traits associated with the development of addictions. In so doing, this study will allow the exploration of the neurobiological basis for SUD risk. [unreadable] [unreadable] [unreadable]